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    <title>clCreateEventFromEGLsyncKHR</title>
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    <div class="refentry">
      <a id="id-1"></a>
      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="clCreateFromGLBuffer"></a>
        <h1>clCreateEventFromEGLsyncKHR</h1>
        <p>
            Creates a linked event object.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
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              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                        <a class="link" href="abstractDataTypes.html" target="pagedisplay">cl_event</a>
                     <strong class="fsfunc">
                        clCreateEventFromEGLsyncKHR
                    </strong>
                (</code>
                <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_context</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">context</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>CLeglSyncKHR <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">sync</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>CLeglDisplayKHR <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">display</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">cl_int</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*errcode_ret</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="parameters"></a>
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term"> <code class="varname"> context </code> </span>
            </dt>
            <dd>
              <p>
                       A valid OpenCL context
                      created from an OpenGL context or share group, using the
                      <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a>
                      extension.
                    </p>
            </dd>
            <dt>
              <span class="term"> <code class="varname"> sync </code> </span>
            </dt>
            <dd>
              <p> 
                        The name of a sync object of type <code class="constant">EGL_SYNC_FENCE_KHR</code> 
                        created with respect to 
                        EGLDisplay <code class="varname">display</code>.
                    </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
            An event object may be created by linking to an EGL sync object. Completion of such an event 
            object is equivalent to waiting for completion of the fence command associated with the linked 
            EGL sync object.
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
            The parameters of an event object linked to 
            an EGL sync object will return the following values 
            when queried with 
            <a class="citerefentry" href="clGetEventInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetEventInfo</span></span></a>:
        </p>
        <p>
          </p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem">
              <p>
                The <code class="constant">CL_EVENT_COMMAND_QUEUE</code> of 
                a linked event is NULL, because the event is not 
                associated with any OpenCL command queue.
              </p>
            </li>
            <li class="listitem">
              <p>
                The <code class="constant">CL_EVENT_COMMAND_TYPE</code> of a linked event is 
                <code class="constant">CL_COMMAND_EGL_FENCE_SYNC_OBJECT_KHR</code>, indicating that the event is 
                associated with a EGL sync object, rather than an OpenCL command.
              </p>
            </li>
            <li class="listitem">
              <p>
                The <code class="constant">CL_EVENT_COMMAND_EXECUTION_STATUS</code> 
                of a linked event is either 
                <code class="constant">CL_SUBMITTED</code>, indicating that the 
                fence command associated with the sync object has 
                not yet completed, or <code class="constant">CL_COMPLETE</code>, 
                indicating that the fence command has completed.
              </p>
            </li>
          </ul>
        </div>
        <p>
        </p>
        <p>
        <code class="function">clCreateEventFromEGLsyncKHR</code> performs an implicit 
        <a class="citerefentry" href="clRetainEvent.html"><span class="citerefentry"><span class="refentrytitle">clRetainEvent</span></span></a> 
        on the returned event 
        object. Creating a linked event object also 
        places a reference on the linked EGL sync object. 
        When the event object is deleted, the reference 
        will be removed from the EGL sync object.
      </p>
        <p>
        Events returned from <code class="function">clCreateEventFromEGLsyncKHR</code> 
        may only be consumed by 
        <code class="function">clEnqueueAcquire***</code> commands. 
        Passing such events to any other CL API that enqueues 
        commands will generate a <span class="errorname">CL_INVALID_EVENT</span> error."
      </p>
        <p>
        Event objects can also be used to reflect the status 
        of an EGL fence sync object. The sync object
        in turn refers to a fence command executing in 
        an EGL client API command stream. This 
        provides another method of coordinating sharing 
        of EGL / EGL client API objects with OpenCL.
        Completion of EGL / EGL client API commands may 
        be determined by placing an EGL fence 
        command after commands using <code class="function">eglCreateSyncKHR</code>, 
        creating an event from the resulting EGL 
        sync object using 
        <code class="function">clCreateEventFromEGLsyncKHR</code> 
        and then specifying it in the <code class="varname">event_wait_list</code>
        of a <code class="function">clEnqueueAcquire***</code> command. 
        This method may be considerably more efficient than 
        calling operations like <code class="function">glFinish</code>, 
        and is referred to as <span class="emphasis"><em>explicit synchronization</em></span>. 
        The application is 
        responsible for ensuring the command stream 
        associated with the EGL fence is flushed to ensure 
        the CL queue is submitted to the device. 
        Explicit synchronization is most useful when an EGL 
        client API context bound to another thread 
        is accessing the memory objects.
      </p>
      </div>
      <div class="refsect1">
        <a id="errors"></a>
        <h2>Errors</h2>
        <p>
          Returns a valid OpenCL event object and <code class="varname">errcode_ret</code> is set to
          <span class="errorname">CL_SUCCESS</span> if the event object is created successfully.
          Otherwise, it returns a NULL value with one of the following error values returned
          in <code class="varname">errcode_ret</code>:
        </p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_CONTEXT</span> if <code class="varname">context</code> is not
              a valid context or was not created from a GL context.
            </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_EGL_OBJECT_KHR</span> if <code class="varname">sync</code>
              is not a valid EGLSyncKHR object of type
              <code class="constant">EGL_SYNC_FENCE_KHR</code> created with 
              respect to EGLDisplay <code class="varname">display</code>.
            </li>
          </ul>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />

            <a href="https://www.khronos.org/registry/cl/specs/opencl-2.0-extensions.pdf#page=160" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="cl_khr_egl_event.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_egl_event</span></span></a>,
            <a class="citerefentry" href="clEnqueueAcquireEGLObjectsKHR.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireEGLObjectsKHR</span></span></a>,
            <a class="citerefentry" href="clEnqueueAcquireGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireGLObjects</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2013 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
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the condition that this copyright notice and permission notice shall be included
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